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Introduction to Data Communications
10. Brief History of Networking
Telecommunications FDM is based on channel groups. The basic channel is called the Voice Channel and it has a bandwidth of 0-4 kHz. The channel groups are based on multiples of the voice channel:
Multiplex Level |
|
Voice Circuits |
|
Freq Band (kHz) |
|
BW (kHz) |
Voice Channel |
|
1 |
|
0 - 4 |
|
4 |
Group |
|
12 |
|
60 - 108 |
|
48 |
Supergroup |
|
60 |
|
312 - 552 |
|
240 |
Mastergroup |
|
600 |
|
564 - 3,084 |
|
2520 |
Jumbogroup |
|
3600 |
|
564 - 17,548 |
|
16984 |
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The Mastergroup and Jumbogroup have guard-bands added to the bandwidth.
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A Group is made of 12 Voice Channels.
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A Supergroup (60 Voice channels) is made of 5 Groups (12 Voice Channels).
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A Mastergroup (600 Voice Channels) is made of 10 Supergroups (60 Voice Channels).
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A Jumbogroup (3600 Voice Channels) is made of 6 Mastergroups (600 Voice Channels).
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